What is 8.49x10^-7 in decimal form? 0.0000000849 0.000000849 8,490,000 849,000,000

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Acomputer store bought a program at a cost of $10 and sold it for $13. find the percent markup

Mr. vector door is buying two new cowboy hats all together the hats cost $75.12 the second heart cost twice as much as the first hat what is the price of the more expensive at round to the nearest hundredth